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Finding the Fourth Proportional to 81.18, 112.01 and 78.57

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Solution

The fourth proportional to 81.18, 112.01 and 78.57 is: 108.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.18 : 112.01 = 78.57 : x
  2. Step 2: Convert to fraction form
    81.18/112.01 = 78.57/x
  3. Step 3: Cross multiply
    81.18x = 112.01 × 78.57
  4. Step 4: Simplify right side
    81.18x = 8,800.23
  5. Step 5: Solve for x
    x = 8,800.23/81.18
  6. Step 6: Final answer
    x = 108.40

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.